Exchange Online Hybrid: Fixing free/busy issues

Now, I’m just going to come out and say it – this is NOT the only fix for free/busy issues when configuring Exchange Online Hybrid with an on-prem Exchange server. If you’re reading this, then it’s more than likely that you (like me), have been reading countless TechNet articles, blog posts, forum posts, etc. Well, at the end of it all, this was the fix for my free/busy issues, and I thought others might benefit by finding this ahead of time, and hopefully cut out some of the Googling Binging… 😉

The Problem:

Pretty straightforward – users on prem could not see the free/busy status of users in Office 365. I worked my way through every setting I could think of, including (but not limited to) Autodiscover, DNS, permissions, certificate settings, Exchange CU level, to no avail!

The Solution:

Eventually, I came across this TechNet blog post which gave me the answer I needed – now, I will say that I’ve never had to set this before, and never noticed this setting missing on previous hybrid configs, but anyway…

In my on-prem environment, the TargetSharingEpr setting was blank, like so:

Thankfully, the fix for this is simple – run the following from an elevated PowerShell prompt:

I also checked my Exchange Online org settings and found that the TargetSharingEpr was also blank:

Now, I wasn’t having any issues with free/busy in this direction, but I thought I’d go ahead and update it anyway – just in case. Make sure that this time around, you’re connecting to Exchange Online, and not your on-prem Exchange, and point it back to your EWS endpoint: